Excess post-exercise oxygen consumption (EPOC)

21 May 2024

Excess post-exercise oxygen consumption (EPOC), often referred to as the “afterburn effect,” is the increased rate of oxygen intake following strenuous activity. This phenomenon occurs as the body works to restore itself to its pre-exercise state, and it can be particularly pronounced after resistance training. Here’s an explanation of the mechanisms behind EPOC following resistance training:

  1. Replenishing Energy Stores: During resistance training, the body depletes its stores of adenosine triphosphate (ATP) and creatine phosphate (CP). Post-exercise, oxygen is required to help replenish these energy stores, which were used up during the workout.
  2. Removal of Lactate: Intense resistance training can lead to the production of lactate. Post-exercise, the body uses oxygen to convert lactate back to pyruvate, which can then enter the Krebs cycle for further energy production or be used to synthesize glucose in the liver through gluconeogenesis.
  3. Restoring Oxygen Levels in Blood and Muscle: After exercise, oxygen levels in the blood and muscle tissues need to be restored. Hemoglobin and myoglobin, proteins that transport and store oxygen, must be re-oxygenated, which increases oxygen consumption.
  4. Repairing Muscle Tissue: Resistance training causes micro-tears in muscle fibers. Repairing these micro-tears and building stronger muscle fibers is an energy-intensive process that requires oxygen to produce the necessary proteins.
  5. Thermogenic Effects: Exercise increases body temperature, and maintaining this elevated temperature post-exercise consumes additional oxygen. This thermogenic effect helps in dissipating the excess heat produced during the workout.
  6. Hormonal Effects: Resistance training influences hormone levels, such as increasing catecholamines (adrenaline and noradrenaline) and growth hormone, which elevate metabolism and oxygen consumption post-exercise as the body returns to its baseline state.
  7. Increased Heart and Respiratory Rate: After resistance training, heart rate and respiratory rate remain elevated for a period as the body gradually returns to resting levels. This increased activity consumes more oxygen.
  8. Enhanced Metabolic Rate: Resistance training can lead to an increase in the metabolic rate, both during and after exercise. The energy required to sustain an elevated metabolic rate involves greater oxygen consumption.

Overall, EPOC represents the body’s efforts to return to homeostasis after the physiological disturbances caused by resistance training. The extent and duration of EPOC can vary 

depending on the intensity and duration of the workout, the individual’s fitness level, and the specific resistance training protocols used.